% The first summand in analytical approximation of core function
% Usage: y = integ_check_for_K1_1(zeta, CONSTS)

function y = integ_check_for_K1_1(zeta, m, CONSTS)
    a = CONSTS.a;
  
    y = log((abs(zeta))/(2*a)) + 2*sum(1./(2*(1:(abs(m)+1))-1)) - ...
        2*log(2);
end
